1. Field of the Invention
The present invention relates to control systems for roller-blinds or similar structures.
More particularly, the invention relates to a control system for roller-blinds or like structures adapted to be rolled up, which is actuated by an electric motor and reduction gear unit associated with an automatic stop-motion device for stopping the operation of this unit when the roller-blind is in anyone of its two end positions, that is, the upper or lower position.
This roller-blind comprises a plurality of swivel blades kinematically connected to a master blade having at least one end provided with a stud adapted to cooperate with a corresponding fixed rocker. Each rocker comprises, for engagement by said stud, a downward inlet and an upward outlet interconnected by a hollow guide path substantially parallel to the lateral slide grooves of the blind. This hollow guide path has an inclined lower extension diverging from the lateral slide groove and a resilient "lock" permitting the passage of said studs through said inlet only in the upward direction. The control system further comprises, for each stud, a first lower stop point formed in the slide groove above the rocker inlet; at this lower stop point the downward movement of the stud is adapted to be discontinued temporarily; a first upper stop point located in said hollow guide path above the rocker outlet and whereat the upward movement of the stud is also adapted to be discontinued temporarily; a second lower stop point located substantially at the end of said inclined lower extension which correspond to a maximum orientation of said master blade, and a second upper stop point located in the slide grooves above the rocker outlet and whereat the upward movement of the stud is adapted to be discontinued temporarily after said stud has left the hollow guide path of said rocker. The control system further comprises two switches the operation of which is linked to the rotation of the roller-blind winding tube kinematically connected in turn to the motor and reduction gear unit, one of said switches assisting in stopping the motor and reduction gear unit when said stud is at its first upper stop point.
2. The Prior Art
In a known control system of this type (GRADHERMETIC), disclosed in German Pat. No. 1,266,475 to Grau, it is the automatic stop motion device provided for stopping the blind when the latter is fully rolled up or unrolled, which, through its switch controlling the stopping of the blind in its unrolled position, determines simultaneously the first lower stop point of the stud. This additional role of the automatic stop device of the roller- blind consists in providing a functional combination between the blind unrolling movement and the angular setting of the blind blades, so that additional conductors must be provided between the automatic stop motion device and the control case of the control system. Therefore, since the automatic stop motion device is incorporated in the motor and reduction gear unit driving the blind, the wires leading from this unit must compulsorily have special properties and this requirement increases, from the economical standpoint, the difficulty of manufacturing economially a complete range of motor and reduction gear units of different power ratings in parallel with a standard range of existing units of this character.
Besides, in the same prior art control systems, the control switches are connected by twelve to sixteen electrical conductors to the motor and reduction gear unit, to the automatic stop motion device and to the auxiliary double-switch device. This large number of conductors increases the difficulty of installing the motor and reduction gear unit and the control means on the site.
On the other hand, the two switches of the auxiliary device are utilized for controlling directly the stoppage of the motor and reduction gear unit, one switch controlling directly the stoppage of the motor and reduction gear unit, one switch controlling directly this stoppage when the stud is at its first upper stop point, and the other switch controlling directly this stoppage when the stud is at its second upper stop point. It is therefore necessary to use an additional switch for controlling the stoppage of the stud at its second lower stop point, along the inclined extension of the guide path. This additional switch controlling not a low-voltage current but the main voltage current, is housed in a rocker, and two additional electrical conductors are necessary for connecting this rocker to the case of the control device, thus further complicating the installation on the site.
Finally, it is clear that many additional electrical conductors are necessary, and that all these conductors are connected to the case of the control device containing or not the push-botton switches for controlling the movements of the roller-blind and of the swivel blades thereof. The control device according the prior art, which operates electromagnetically, involves the use of a relatively large number (seven) of push-button switches for controlling the blades. The first switch controls the unrolling movement, the second switch controls the rolling movement, the third switch controls the stoppage, the fourth switch controls the swivel movement of the blades to the desired angular position, the fifth and sixth switches control the more or less considerable orientation of the blades, and the seventh switch controls the downward movement of the blind from the orientation position. Even if one disregards the constructional and structural complexity of a control device comprising such a large number of push-button switches, this large number makes the operation of the device particularly complicate for the user. In fact, for carrying out certain control operations, the user may tend to hesitate before selecting the push-button corresponding to the desired movement of the roller-blind. Thus, just for unrolling the blind, the user is confronted with two push, buttons, one to be depressed if the blind is in its desired orientation position, the other to be depressed when the blind is in a position other than this specific orientation position. On the other hand, to move the blind from any intermediate position to a position of maximum orientation, the user must perform three successive operations, each operation being followed by a blind displacement step, and subsequently a reflection time is necessary for the user for selecting the push-button to be depressed. It is the object of the present invention to provide a control system in which the device for automatically stopping the blind in the rolled-up or unrolled position does not play any role in the determination of the first lower stop point of the above-defined stud, and consequently in the blade orientation.